Hereinafter, a general wireless communication system using multiple carriers will be described.
FIG. 1 is a view showing an example of the use of multiple carriers in a general wireless access system.
The multiple carriers in the general wireless access system may employ contiguous carrier aggregation as shown in FIG. 1(a) or non-contiguous carrier aggregation as shown in FIG. 1(b). The combination unit of such carriers is a basic bandwidth unit of a general legacy system (e.g., Long Term Evolution (LTE) in an LTE-advanced system or IEEE802.16e in an IEEE802.16m system). In a multi-carrier environment of general technology, two types of carriers are defined as follows.
First, a primary carrier is the carrier used by a Base Station (BS) and a Mobile Station (MS) to exchange traffic and full PHY/MAC control information defined in the IEEE 802.16m specification. Further, the primary carrier is used for control functions for proper MS operation, such as network entry. Each MS shall have only one carrier it considers to be its primary carrier in a cell.
A secondary carrier is an additional carrier which the MS may use for traffic, only per BS's specific allocation commands and rules, typically received on the primary carrier. The secondary carrier may also include control signaling to support multi-carrier operation.
In the general technology, the carriers of a multi-carrier system based on the above-described primary and secondary carriers may be differently configured as follows.
First, a fully configured carrier is a carrier for which all control channels including synchronization, broadcast, multicast and unicast control signaling are configured. Further, information and parameters regarding multi-carrier operation and the other carriers can also be included in the control channels.
A partially configured carrier is a carrier with only essential control channel configuration to support traffic exchanges during multi-carrier operation.
The primary carrier needs to be fully configured r. In contrast, the secondary carrier may be fully or partially configured according to the user's requirements and the channel state. In addition, when a full configured carrier in the cell is configured as a primary carrier, any MS may be controlled by the primary carrier. In addition, the MS may dynamically use multiple secondary carriers, for data transmission.
Next, a sleep mode of the MS, which is used in the related art, will be described. The MS may configure three types of sleep mode patterns (or Power Saving Classes (PSCs)). In the present specification, “sleep mode type X” has the same meaning as “PSC type X”.
First, Sleep Mode Type 1 which is an example of the sleep mode pattern may be applied to Best Effort (BE) or Non-Real-Time Variable Rate (NRT-VR) type data transmission. In the present pattern, if downlink (DL) traffic is transmitted by a connection, a MOB TRF-IND (Traffic Indication) message is transmitted from a BS to an MS during a listening interval. When the BS sends the MOB TRF-IND message, the MS may complete the active state of the PSC. In addition, the MS may receive all DL data during the listening interval as in a normal operation.
Next, Sleep Mode Type 2 may be applied to Unsolicited Grant Service (UGS) and Real-Time Variable Rate (RT-VR) type data transmission, that is, a service for periodically transmitting or receiving data. The MS may not transmit or receive-a MAC Service Data Unit (MSDU) or a MAC Protocol Data Unit (MPDU) during a sleep interval. However, the MS may also transmit or receive ACK/NACK for data as well as MSDUs or fragments generated by connections during a listening interval.
Finally, Sleep Mode Type 3 may be applied to multicast connections or management operations, such as periodic ranging or the transmission of a neighboring advertisement (MOB_NBR-ADV) message.
If data is transmitted using multiple carriers in the general wireless access system, information about the multiple carriers available to any MS in one cell may be transmitted from a BS to an MS through system information. When the carriers available to the MS are set, the MS should check whether there is data transmitted to the MS on the carriers while monitoring the control channels of all the available carriers.
FIG. 2 is a view showing a method for monitoring multiple carriers by any MS in the general technology. AN MS which enters any cell may receive multi-carrier information including information about multiple carriers available in the cell on a primary carrier. The MS should monitor the control channels during every subframe with respect to all the carriers available to the MS according to the received information about the multiple carriers.